In the initial commit it says:

mkbootimg \
--kernel .Image.gz-dtb \
--ramdisk some_initrd.img \
--pagesize 4096 \
--base 0x0 \
--kernel_offset 0x8000 \
--ramdisk_offset 0x1000000 \
--tags_offset 0x100 \
--cmdline "SOME_CMDLINE" \
--dtb_offset 0x1f00000 \
--header_version 1 \
--os_version 12 \
--os_patch_level 2022-06 \ # or newer
-o boot.img-sony-xperia-pdx223